Appliances that heat up, such as a hair dryer, a clothes
iron, toaster, electric toaster oven, or an electric space
heater all work on the same idea. They change electrical
energy to heat energy.
The devices all plug into a source of electricity.
Electric current runs from your wall socket down the wire
and into the appliance.
Inside each of the appliances are loops of special
mixture of metals. One type is called nichrome. Nichrome is a nickel / chromium alloy.
Electricity cannot pass through this special metal very
easily. The metal slows down the electrons and "holds up" the
current flowing through it. This is called the "resistance"
of the metal. When the resistance of a metal is higher,
the metal will get hot because of the friction of the
electrons in the current of electricity. For more on
resistance, see Chapter 3 of The Energy Story.
As the electricity is forced through the wires, the
wires begin to heat up and glow very hot. If you look
inside your toaster, you'll see those coils or wire glowing
orange. It's those coils or loops of wire that cause the
bread to brown making your toast.
In older toasters, the hot wires heat up a small device
called a thermocouple. When it reaches the right
temperature, which is about the same time as your toast is
properly toasted, it releases a catch allowing the toast to
pop up. At the same time, it shuts off the electricity. In
some newer toasters, the thermocouple is replaced by a small
In a hair dryer, a small fan is turned on at the same
time the heater coils are turned on. The moving air is
forced over the glowing wires, warming the air. The warm
air blows out of the front of the hair dryer and causes the
water in your hair to evaporate and dry.
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